About 20 million Americans have chronic kidney disease while an additional 20 million are at risk. Over the next 10 years, the number of patients in the U.S. with end stage renal disease is expected to double. Some major causes of kidney dysfunction include hypertension, diabetes, lupus erythematosus, chemotherapy and immuno-suppression therapy. In all these instances, it is essential to have an accurate test of kidney function to determine the most appropriate therapeutic intervention. Preventing or slowing the progression of renal disease through early recognition of impaired renal function will reduce the number of patients with end stage renal disease and also prevent or reduce the need for dialysis and kidney transplantation. Glomerular Filtration Rate (GFR) is one of the best indexes of kidney function and it is determined by measuring the disappearance of certain agents from the blood and their appearance in urine. Although commonly used, the accurate estimation of GFR from serum creatinine is unreliable and insensitive as a marker of chronic kidney disease. Conversely, Inulin and radiolabeled Iothalamate provide an accurate measurement of GFR but Inulin is too expensive for common use and Iothalamate is difficult to assay because it requires either iodine-125 radiolabeling or expensive and cumbersome HPLC analysis. This Phase II SBIR proposal describes the development of a small bench-top device that can accurately, rapidly (5 minutes), and conveniently measure "cold" (non-radioactively labeled) Iothalamate in blood and urine samples that will render the usage of radioactively labeled Iothalamate and burdensome HPLC assays obsolete. During the Phase I project, Lynntech designed, fabricated, assembled, and tested a breadboard Iothalamate detection system from commercially available, off-the-shelf components. The system demonstrated sufficient sensitivity (< 20 ppm) in plasma and urine and sample analysis was complete in 5 minutes with minimal sample manipulation. The Phase II workplan describes the optimization of the detection method and the design, assembly, and testing of a fully-integrated bench-top device. The performance of the bench-top device will be compared to an HPLC method developed by our collaborator at the Indiana School of Medicine. The Phase II research also includes the identification of disposable components and process automation in the bench-top system. Glomerular Filtration Rate (GFR) is one of the best indexes of kidney function and it is determined by measuring the disappearance of certain agents from the blood and their appearance in urine. Currently available methods for determination of GFR markers are either too expensive, difficult to assay or require the use of radio-labeled markers. Lynntech's inexpensive and easy to use system can accurately detect non- radiolabeled GFR markers in plasma and urine which will enable the rapid and convenient determination of GFR. [unreadable] [unreadable] [unreadable]